3-Nitro-4-methylbenzene sulfon-2-chloro-4-nitroanilide and fungicidal composition for the control of plant diseases containing same

ABSTRACT

3-nitro-4-methylbenzene sulfon-2-chloro-4-nitroanilide ##STR1## as a novel compound as well as fungicidal composition containing the compound as the active ingredient. The compound of the invention is markedly effective in controlling plant diseases and, in particular, clubroot disease of Brassica spp., has no toxicity to men, beasts, and fishes, exerts no phytotoxicity on crops, has neither irritant nor unpleasant odor, and manifests its excellent fungicidal effect at low concentrations. Accordingly, it is ideally useful in fungicidal composition.

TECHNICAL FIELD

This invention relates to 3-nitro-4-methylbenzene sulfon-2-chloro-4-nitroanilide as a novel compound and fungicidal composition for the control of plant diseases containing the compound as the active ingredient.

BACKGROUND ART

It is an important problem in agriculture to diminish or eliminate injury by continuous cropping. Especially in countries and districts having a limited area of cultivated land, crops must be repeatedly planted through the year and, therefore, continuous cropping is unavoidable.

Under these conditions, biological factors associated with the soil interfere with the growth of various crops such as vegetables, legumes, potatoes, strawberry, tobacco, devil's-tongue, chrysanthemum, carnation, stock, mulberry, apple tree, upland rice, and the like, so that farmers suffer heavy losses. Moreover, the situation goes on getting worse from year to year.

Conventionally, the control of plant diseases and, in particular, soil-borne diseases is very difficult and there is a continuing demand for the development of excellent fungicides. By way of example, the damage due to clubroot disease of Brassica spp. shows a tendency to increase from year to year. That is, important vegetables (such as cabbages, Chinese cabbages, turnip, and the like) indispensable to the dietary life of men are being considerably damaged by this clubroot disease.

At present, various attempts are being made to control soil-borne diseases by means of fungicides. However, commercially available fungicides fail to produce desirable results and cannot be regarded as preferable from a practical point of view. More specifically, in the existing circumstances, none of the commerically available soil fungicides are satisfactory because they have the disadvantages of failing to produce their fungicidal effect unless used at high concentrations, tending to remain in the crop plants or the soil, having very high toxicity to men and beasts, tending to exert phytotoxicity on the crop, and/or having an irritant or an unpleasant odor.

For example, mercury compounds have very high toxicity and volatile substances such as methyl bromide and chloropicrin tend to give off a toxic and irritant gas, so that they may give rise to the problem of environmental pollution. Pentachloronitrobenzene (PCNB) fails to effectively control clubroot disease of Brassica spp., unless applied to the crop in large amounts. Moreover, this compound can hardly be decomposed owing to its stable chemical structure, thus involving a possibility of soil pollution. Furthermore, PCNB tends to be accompanied by hexachlorobenzene, as an impurity, which is difficult to separate during the manufacture of PCNB. It is well known that this compound is undesirable because it remains in the soil for a long period of time and also has high toxicity. Besides, methyl isothiocyanate requires repeated degassing operations in order to avoid its phytotoxicity. Nevertheless, the possibility of phytotoxicity cannot completely be eliminated.

Benzene sulfonanilide and its derivatives are known for a long time, but only a little is known about analogous compounds having their aromatic ring substituted by a nitro group. Japanese Patent Publication No. 41638/'71 discloses 2-nitrobenzene sulfone-2,4-dichloroanilide which is effective in controlling citrus canker. Japanese Patent Publication No. 15119/'72 discloses three nitro-substituted benzene sulfonanilides (i.e., 3-nitrobenzene sulfonanilide, 3-nitrobenzene sulfone-4-chloroanilide, and 3-nitrobenzene sulfone-3,4-dichloroanilide), which are described as being effective in controlling brown leaf spot and pellicularia disease of rice. Japanese Patent Laid-Open No. 31655/'82 discloses 2-nitrobenzene sulfone-2,6-diethylanilide, which is described as being effective in controlling rice blast.

As described above, a number of nitro-substituted benzene sulfonanilides are known in the prior art. However, nothing is known about the nitro-substituted benzene sulfonanilides having both aromatic rings substituted by nitro groups. Moreover, neither experiment on the ability of benzene sulfonanilide and its derivatives to control soil-borne diseases, nor literature disclosing their effectiveness in controlling soil-borne diseases can be found.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide a novel nitrobenzene sulfonanilide derivative.

It is another object of the present invention to provide a novel fungicidal composition which is markedly effective in controlling plant diseases and, in particular, clubroot disease of Brassica spp.

The above objects of the present invention are accomplished by providing, as the novel compound, 3-nitro-4-methylbenzene sulfon-2-chloro-4-nitroanilide, as well as by providing the fungicidal composition for the control of plant diseases which contain the compound as the active ingredient.

The compound of the present invention has neither toxicity to men and beasts nor toxicity to fishes and shellfishes, exerts no phytotoxicity on crops, has neither irritant nor unpleasant odor, and can control plant diseases at so low concentrations that the amount of fungicide used and hence the possibility of soil pollution can be diminished. Thus, the compound can ideally be used as fungicide for the control of plant diseases.

BEST MODE FOR CARRYING OUT THE INVENTION

The 3-nitro-4-methylbenzene sulfon-2-chloro-4-nitroanilide of the present invention can be prepared by reacting 3-nitro-4-methylbenzene sulfonyl chloride with 2-chloro-4-nitroaniline in the presence of pyridine. The reaction may suitably be carried out in inert solvents such as toluene, xylene, nitrobenzene, and the like. However, where pyridine is used in large amounts, it can also be utilized as the solvent. The reaction temperature can range from 70° to 200° C., the preferred range being from 100° to 140° C. The reaction time can range from 5 to 30 hours, the preferred range being from 5 to 20 hours.

The method for preparing the compound of the present invention is more specifically explained with reference to the following example.

EXAMPLE [Synthesis of 3-nitro-4-methylbenzene sulfone-2-chloro-4-nitroanilide]

A solution was prepared by dissolving 3.4 g (0.02 mole) of 2-chloro-4-nitroaniline in 30 ml of pyridine. While this solution was being stirred at 80°-90° C., 4.8 g (0.02 mole) of 3-nitro-4-methylbenzene sulfonyl chloride was added slowly thereto. Subsequently, this mixture was stirred at 100°-110° C. for 5 hours to complete the reaction. The resulting reaction mixture was cooled to room temperature, poured into 100 ml of cold water, and allowed to stand for a while. The precipitate so formed was extracted twice by shaking with 200 ml portions of ethyl acetate. This extract was washed with water, dehydrated over anhydrous sodium sulfate, and then stripped of ethyl acetate under reduced pressure. The residue was subjected to silica gel chromatography (using a 3:1 mixture of toluene and ethyl acetate as the developing solvent) to obtain 4.5 g of a desired product in a 60% yield. This product was a pale-yellow crystalline substance, and its melting point was 175°-177° C.

Elemental analysis:

    ______________________________________                                                     C    H        Cl     N      S                                      ______________________________________                                         Calculated value (%)                                                                         41.99  2.69     9.56 11.31  8.61                                 for C.sub.13 H.sub.10 ClN.sub.3 O.sub.6 S                                      Found value (%)                                                                              42.26  2.55     9.68 11.36  8.55                                 NMR: δ .sub.TMS.sup.DMSO D.sbsp.6   = 2.60 (3H, S, CH.sub.3)             IR: ν .sub.max.sup.KBr (cm.sup.-1) = 3260 (NH)                              ______________________________________                                    

The fungicidal composition of the present invention can take any desired form suitable for use as agricultural or horticultural preparations, particularly fungicidal formulations, provided that it contains 3-nitro-4-methylbenzene sulfor-2-chloro-4-nitroanilide as the active ingredient. For example, according to the intended purpose, the compound of the present invention may be used as such or may be combined with suitable carriers to make it into various forms such as dusts, granules, fine granules, wettable powder, flowable formulations, emulsifiable concentrates, and the like. Preferably, the amount of active ingredient present in such a composition is in the range of 2 to 5% for dusts, granules, and fine granules; in the range of 40 to 60% for wettable powders and flowable formulations; and in the range of 30 to 50% for emulsifiable concentrates.

Specific examples of useful solid carriers include clay, talc, kaolin, bentonite, diatomaceous earth, silica, calcium carbonate, calcium sulfate, and the like. Specific examples of useful liquid carriers include water, aromatic hydrocarbons, aliphatic hydrocarbons, alcohols, esters, ketones, acid amides, fatty acids, animal and vegetable oils, various surface active agents, and the like. Moreover, suitable adjuvants such as spreaders, emulsifiers, wetting agents, dispersants, sticking agents, and the like may be added in order to ensure effectiveness. Furthermore, the compound of the present invention may be used in admixture with various agricultural materials such as herbicides, insecticides, miticides, other fungicides, soil conditioners, fertilizers, and the like, or may be used as additives.

The fungicidal composition of the present invention can be used by sprinkling it directly on the crop plant whose disease is to be controlled. Besides, according to the need, it can be applied to the growing environment of the crop plant, i.e., the surface of the water, the ground, or the like, and can be mixed in the soil.

The amount of fungicidal composition used can vary according to the intended purpose. In the case of emulsifiable concentrates, wettable powders, and the like, it is usually desirable to spray them in the form of a dispersion which contains the active ingredient (i.e., the compound of the present invention) at a concentration of 10 to 1,000 ppm. However, where a small volume of highly concentrated dispersion is used or a dispersion is sprayed by means of aircraft, the concentration of the dispersion may be increased as desired. In the case of dusts, granules, and the like, the amount of fungicidal composition used may be changed according to the size of the crop plant, the density of the pathogenic organism, its sensitivity to the fungicide, and the like. However, they can usually be used in substantially the same amount as conventional fungicides.

Where it is desired to control clubroot disease of Brassica spp., the compound of the present invention is preferably used as such or in any of the above-described forms and applied, prior to the planting of the crop, in such an amount as to provide 5 to 20 kg of the active ingredient per hectare.

Several examples of fungicidal composition containing the compound of the present invention as the active ingredient are described hereinbelow. However, it is to be understood that the type and proportion of additives used are not limited thereto and the content of the active ingredient can vary widely.

Fungicidal Composition 1 [Dust]

A mixture of 10.5 g of the compound of the present invention, 2.0 g of Carplex #80 (white carbon; a product of Shionogi Pharmaceutical Co.), and 87.5 g of clay was pulverized to form a dust.

Fungicidal Composition 2 [Wettable powder]

A mixture of 50.5 g of the compound of the present invention, 5.0 g of Sorpol 5039 (a mixture of a special nonionic-anionic surface active agent and white carbon; a product of Toho Chemicals Co.), and 44.5 g of Radiolite #200 (calcined diatomaceous earth; a product of Showa Chemicals Co.) was pulverized to form a wettable powder.

Fungicidal Composition 3 [Granules]

The pulverized compound of the present invention (20.5 g) was intimately mixed with 2.0 g of Gohsenol GL-05S (PVA; a product of Nihon Synthetic Chemistry Co.), 2.0 g of Sun Extract P-252 (lignin sulfonic acid sodium salt; a product of Sanyo Kokusaku Pulp Co.), and 75.5 g of clay. This mixture was moistened with an appropriate amount of water and then granulated by means of an extruding machine. The resulting granules were air-dried at 70°-80° C., crushed, and then adjusted to a particle size of 0.5-1 mm by means of a classifier.

Fungicidal Composition 4 [Flowable formulation]

The compound of the present invention (40.0 g) was mixed with 10.0 g of lignin sulfonic acid sodium salt, 1.0 g of gum arabic, and 49.0 g of water. This mixture was pulverized with a sand grinder to form a flowable formulation.

Next, the effects of the present invention are discussed hereinbelow. The diseases of agricultural and horticultural crops which are at present difficult to control effectively include bactrial diseases, virus diseases, and various soil-borne diseases. The compound of the present invention has very excellent performance as fungicide for the control of plant diseases, in that it is effective in controlling bacterial diseases (e.g., bacterial leaf blight of rice) and soil-borne diseases (e.g., clubroot disease of Brassica spp.). Its effectiveness is more fully illustrated by the following evaluation tests.

Evaluation Test 1 [Test for protection against clubroot diseases of Brassica spp.]

A wettable powder prepared according to the procedure of Fungicidal Composition 2 was suspended in 20 ml of water, and was added to and mixed in 1.0 kg of soil contaminated with the causal organism of clubroot disease of Brassica spp. (i.e., Plasmodiophora brassicae) so as to provide the specified amount of the active ingredient. This soil was charged into No. 5 pots and 20 seeds of Chinese cabbage (Brassica rupa L. var. Komatsuna Hara) were sown in each of the pots. These pots were placed on an outdoor stand. Six weeks after sowing, the roots of the growing plants were washed in running water and examined for the presence of affection. Then, the rate of protection was calculated according to the following equation. ##EQU1##

As control fungicides, PCNB (containing 75% of the active ingredient), the compound described in Japanese Patent Publication No. 41638/'71 (i.e., 2-nitrobenzene sulfone-2,4-dichloroanilide) and the compounds described in Japanese Patent Publication No. 15119/'72 (i.e., 3-nitrobenzene sulfonanilide, 3-nitrobenzene sulfone-4-chloroanilide, and 3-nitrobenzene sulfone-3,4-dichloroanilide) were used. This test was carried out in triplicate and the rates of protection for the respective runs were averaged. The results thus obtained are shown in Table 1.

                  TABLE 1                                                          ______________________________________                                                    Amount of active                                                                            Rate of                                                           ingredient per pot                                                                          protection                                             Compound Tested                                                                           (mg)         (%)       phytotoxicity                                ______________________________________                                         The compound of                                                                           5            91.5      None                                         the present                                                                               10           100.0     "                                            invention  20           100.0     "                                            2-nitrobenzene                                                                            5            12.0      "                                            sulfone-2,4-                                                                              10           42.5      "                                            dichloroanilide                                                                           20           52.0      "                                            (control)                                                                      3-nitrobenzene                                                                            5            4.2       "                                            sulfoneanilide                                                                            10           14.1      "                                            (control)  20           23.4      "                                            3-nitrobenzene                                                                            5            3.5       "                                            sulfone-4- 10           11.9      "                                            chloroanilide                                                                             20           19.7      "                                            (control)                                                                      3-nitrobenzene                                                                            5            1.4       "                                            sulfone-3,4-                                                                              10           35.4      "                                            dichloroanilide                                                                           20           52.4      "                                            (control)                                                                      PCNB       5            10.5      "                                            (control)  10           45.6      "                                                       20           61.5      "                                                       40           75.8      "                                            No treatment                                                                              --           0.0       "                                            ______________________________________                                    

Evalution Test 2 [Field test for protection against clubroot disease of Brassica spp.]

To the whole surface of a field in which this disease had habitually occurred was applied a complex fertilizer in such an amount as to provide 30 kg each of N, P₂ O₅, and K₂ O per 10 ares. After being plowed, the field was divided into 4 m×5 m plots each having an area of 20 m². A dust prepared according to the procedure of Fungicidal Composition 1 was uniformly spread in the specified amount and intimately mixed with the soil by means of a small cultivator. On the following day, seedlings of Chinese cabbage (var. Muso) which had been grown in paper pots for three weeks were planted with a ridge breadth of 60 cm and a distance between plants of 45 cm. Seven weeks after planting, the roots of the plants were dug out and examined for the degree of affection. The rate of affection was calculated, together with the index of affection as defined by the following equation: ##EQU2## where n₀ : number of individuals in which no swellings are observed.

n₁ : number of individuals in which swellings are observed solely on lateral roots.

n₂ : number of individuals in which swellings are observed both on the main root and on lateral roots, but they are not marked.

n₃ : number of individuals in which marked swellings are observed both on the main root and on lateral roots.

N: Total number of examined individuals.

Besides, the overground portion of the plants was examined for yield. A PCNB dust (containing 20% of the active ingredient) was used as a control fungicide. This test was carried out in triplicate and the results thus obtained are shown in Table 2.

                  TABLE 2                                                          ______________________________________                                                 Amount of                                                                      active                                                                         ingredient                                                                               Rate of                                                      Compound                                                                               used      affection                                                                               Index of                                                                              Yield* Phyto-                                tested  (kg/ha)   (%)      affection                                                                             (tons/ha)                                                                             toxicity                              ______________________________________                                         The com-                                                                               10        12.0     0.25   145.0  None                                  pound of                                                                               20        2.5      0.06   156.0  "                                     the present                                                                            40        0.0      0.00   160.3  "                                     invention                                                                      PCNB    40        100.0    2.68   80.2   "                                     (control)                                                                              60        94.5     2.21   100.2  "                                     No      --        100.0    3.00   24.0   "                                     treatment                                                                      ______________________________________                                          *The weight of Chinese cabbages prepared for commercial purposes by            removing 5-7 outer leaves.                                               

Evalution Test 3 [Test for fungicidal activity against the organism of bacterial leaf blight of rice]

In petri dishes of 9 cm diameter, 15 ml of a 1.5% water agar medium was poured and solidified. Then, 5 ml of a test medium containing the causal organism of bacterial leaf blight of rice (i.e., Xanthomonas oryzae) was poured thereon and solidified to form an upper layer. A paper disc of 7 mm diameter was soaked in a 1000 ppm acetone solution of the compound of the present invention for 30 minutes and then placed on the test medium. The Petri dish was incubated at 28° C. for 24 hours and the diameter of the resulting inhibited circle was measured to evaluate the fungicidal activity of the compound. The test medium had the following composition.

    ______________________________________                                         Composition of Test Medium (in 1 liter of water)                               Component          Quantity                                                    ______________________________________                                         Sodium glutamate       2.0     g                                               Monopotassium phosphate                                                                               2.0     g                                               Magnesium chloride     1.0     g                                               Ferrous sulfate        0.1     g                                               Sucrose                20.1    g                                               Yeast extract          2.0     g                                               Peptone                5.0     g                                               Agar                   15-20   g                                               ______________________________________                                    

As control fungicides, the compound described in Japanese Patent Publication No. 41638/'71 and streptomycin sulfate were used in the form of 1000 ppm acetone solutions. The results thus obtained are shown in Table 3.

                  TABLE 3                                                          ______________________________________                                                          Diameter of inhibited                                         Compound tested  circle (cm)                                                   ______________________________________                                         The compound of the                                                                             3.2                                                           present invention                                                              2-nitrobenzene   2.8                                                           sulfone-2,4-dichloroanilide                                                    Streptomycin sulfate                                                                            2.5                                                           ______________________________________                                    

Evaluation Test 4 [Test for protection against bacterial leaf blight of rice]

A group of 10 seedlings of paddy rice (var. Kinmaze) was planted in pots and cultivated in a greenhouse. As soon as the plants reached the 6-leaf stage, a wettable powder prepared according to the procedure of Fungicidal Composition 2 was dispersed in water to a predetermined concentration and the resulting dispersion was uniformly sprayed on the stems and leaves in an amount of 20 ml per pot.

After the spray dried up, 10 latest developing leaves for each pot were inoculated, by multiple needling, with a suspension of the causal organism of bacterial leaf blight of rice (i.e., Xanthomonas oryzae) which had previously been cultured in Wakimoto's medium.

Two or three weeks after inoculation, the spots of affected leaves were observed. The rate of protection was calculated according to the following equation. ##EQU3##

As control fungicides, the compound described in Japanese Patent Publication No. 41638/'71 (i.e., 2-nitrobenzene sulfone-2,4-dichloroanilide) and a phenazine wettable powder (containing 10% of phenazine oxide; a product of Meiji Seika Co.) were used. The results thus obtained are shown in Table 4.

                  TABLE 4                                                          ______________________________________                                                 Concentration of                                                                              Rate of                                                 Compound                                                                               active ingredient                                                                             protection                                              tested  in spray (ppm) (%)       Phytotoxicity                                 ______________________________________                                         A*      500            92.5      None                                          B*      500            87.5      None                                          C*      500            57.0      None                                          ______________________________________                                          *A: The compound of the present invention.                                     B: 2Nitrobenzene sulfone2,4-dichloroanilide (control).                         C: Phenazine wettable powder (control).                                  

As can be seen from the above-described evaluation tests, the compound of the present invention is effective in controlling plant diseases caused by either bacteria or fungi and, therefore, has very excellent performance as fungicide for agricultural and horticultural use. 

We claim:
 1. 3-nitro-4-methylbenzene sulfon-2-chloro-4-nitroanilide.
 2. A fungicidal composition containing, as the active ingredient, 3-nitro-4-methylbenzene sulfon-2-chloro-4-nitro-anilide in the amount of 2 to 60 weight percent and an agriculturally-accepted carrier.
 3. The fungicidal composition of claim 2 which is effective in controlling soil-borne plant diseases.
 4. The fungicidal composition of claim 2 which is effective in controlling clubroot disease of Brassica spp.
 5. A method of controlling clubroot disease of Brassica spp. which comprises, prior to the planting of a crop of the genus Brassica, applying 3-nitro-4-methyl-benzene sulfon-2-chloro-4-nitroanilide to the field in an amount of 5 to 20 kilograms per hectare. 